From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH] m68k: fix "bad page state" oops on ColdFire boot Date: Mon, 18 Jun 2018 08:58:11 +0200 Message-ID: References: <20180618060426.24497-1-gerg@linux-m68k.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20180618060426.24497-1-gerg@linux-m68k.org> Sender: linux-kernel-owner@vger.kernel.org To: Greg Ungerer Cc: Matthew Wilcox , Linux/m68k , Linux Kernel Mailing List List-Id: linux-m68k@vger.kernel.org Hi Greg, On Mon, Jun 18, 2018 at 8:06 AM Greg Ungerer wrote: > Booting a ColdFire m68k core with MMU enabled causes a "bad page state" > oops since commit 1d40a5ea01d5 ("mm: mark pages in use for page tables"): > > BUG: Bad page state in process sh pfn:01ce2 > page:004fefc8 count:0 mapcount:-1024 mapping:00000000 index:0x0 > flags: 0x0() > raw: 00000000 00000000 00000000 fffffbff 00000000 00000100 00000200 00000000 > raw: 039c4000 > page dumped because: nonzero mapcount > Modules linked in: > CPU: 0 PID: 22 Comm: sh Not tainted 4.17.0-07461-g1d40a5ea01d5 #13 > > Fix by calling pgtable_page_dtor() in our __pte_free_tlb() code path, > so that the PG_table flag is cleared before we free the pte page. > > Signed-off-by: Greg Ungerer > CC: Matthew Wilcox > --- > arch/m68k/include/asm/mcf_pgalloc.h | 1 + > 1 file changed, 1 insertion(+) > > Matthew: I came across this thread at https://lkml.org/lkml/2018/6/17/163 > about a similar problem with openrisc. Based on that I came up > with this fix for m68k/ColdFire. Fixes the issue for me. > > diff --git a/arch/m68k/include/asm/mcf_pgalloc.h b/arch/m68k/include/asm/mcf_pgalloc.h > index 8b707c249026..8c441eb57b80 100644 > --- a/arch/m68k/include/asm/mcf_pgalloc.h > +++ b/arch/m68k/include/asm/mcf_pgalloc.h > @@ -44,6 +44,7 @@ extern inline pmd_t *pmd_alloc_kernel(pgd_t *pgd, unsigned long address) > static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t page, > unsigned long address) > { > + pgtable_page_dtor(page); > __free_page(page); > } Do you need a call to pgtable_page_dtor() in pte_free(), too? On x86 (and motorola_pgalloc.h and sun3_pgalloc.h FWIW), both functions call pgtable_page_dtor(). Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds